Sponge rubber body of different densities



March 14, 1939. I R. MINOR 2,

SPONGE RUBBER BODY OF DTFFERENT DENSTTIES Original Filed May 16, 1936 INVENTOR! HENRY. R- MINOR g x; Z

A TTORNEYS.

Patented Mar. 14, 1 939 UNlTED STATES PATENT OFFICE SPONGE RUBBER BODY OF DIFFEREN DENSITIES Henry R. Minor, Dayton, Ohio, assignor to IndustrialProcess Corporation, Dayton, Ohio, a corporation of New York Original application May 16, 1936, Serial No.

80,191. Divided and this application Decem- 'ber 21, 1936, Serial No. 116,959

1 Claim.

. It is a particular object of my invention to provide a sponge rubber seat cushion having areas of greater density where the greater Weight is applied and to combine with this arrangement a seat cushion having a proper configuration for the reception of the weight of the body and the form of the body.

It is a further object to provide a method of loading a mold for forming such a seat cushion of sponge rubber.

This application is a division of my application Serial No. 80,191, filed May 16, 1936.

Referring to the drawing:

Figure 1 is a top plan View of the cushion.

Figure 2 is a side elevation thereof.

) Figure 3 is a section on the line 33 of Figure 1 looking in the direction of the arrows.

Figure 4 is a top plan view of the moldpartially loaded.

Figure 5 is a section on the line 5-5 of Figure 4 looking in the direction of the arrows.

Referring to the drawing in detail, I represents a sponge rubber seat cushion, which may be either of a continuous body of sponge rubber of different densities and different areas, as at 2 and 3, or it may be formed of a seat portion 4 and vertical members 5 forming tubular areas 6 of difierent portions of the structure of greater density than others. The latter method is: the preferred method of manufacturing this cushion.

If desired, the surface of the cushion may be formed with depressions 1 and. the elevated areas 8 in order to provide a shaped surface for the reception of the body of the person sitting upon the cushion. Such depressed areas are ovoid in shape, as indicated in Figure 3.

In the manufacture of such a cushion, I prefer to use a sheet metal mold having side Walls, top and bottom of sheet metal designated 9 with a plurality of open-ended tubes 9 extending into the interior of the mold. The tops of these tubes are closed as at H with the exception of a few perforations 12.

These tubes are staggered with respect to one another and arranged in rows. Between the rows are inserted in a vertical position the rubber stock sheets l3 which are turned horizontally over the tops of the tubes as at M with their edges l5 overlapping the next adjacent portion M of the strip.

When it is desired to provide areasof greater density, either the stock sheets thus. inserted may be made of a material as hereinafter described of greater density or additional sheets l6 may be inserted of the same or greater density than the adjacent sheets of stock. These sheets I6 will be of lesser length and will be confined to the particular area which it is desired to make of denser material to form the areas 2.

When the stock is thus arranged, the mold is closed and placed in a vulcanizer for vulcanization and curing in accordance with the practices outlined in my co-pending application Serial No. 59,625, filed January 17, 1936.

My process consists broadly of arranging the stock on edge with a portion horizontally disposed overlapping the next adjacent strip of stock; and of impregnating the stock with car'- bon dioxide gas under pressure; and thereafter applying the necessary heat as described in my co-pending application to bring about curing and vulcanization of the sponge rubber stock in sponge condition and of regulating that sponge as to its character and nature by the regulation of the escape of the carbon dioxide gas.

For instance, I find I am enabled to bring the pressure of impregnation up to 140 pounds to a square inch and gradually decrease it to zero while using a temperature as indicated.

When it is desired to make the stock of rubber denser in other areas, I have found such expedients as loading with clay, whiting and blanc fix, and even increasing the proportion of carbon black, a satisfactory means of increasing the density of the stock. Any of the Well known methods of increasing the density of stock may be employed. Those I mention are merely typical.

It is understood that where the term diiferent densities is used there is meant not only the change in mass per unit volume but also those changes in physical properties resulting in. increased strength, resilience and resistance to defiection as may be obtained by the skillful compounder.

It will be understood that I desire to comprehend within my invention such modifications as come within the scope of my claim and my invention.

Having thus fully described my invention, what I claim as new and desire to secure by Letters Patent, is:

In a method of forming a homogeneous sponge rubber body comprising sections of varying densities, arranging stock rubber sheets of diiferent physical properties in overlapping position with horizontal and vertical portions enclosing mold projections with the vertical portions of the stock arranged between the mold projections; enclosing the mold in an atmosphere of carbon dioxide gas 7 under pressure; and so regulating the temperature to which the stock and mold are subjected and the rate of escape of the carbon dioxide gas that a homogeneous body of sponge rubber of predetermined configuration having certain integral sections of different physical properties and densities is formed.

HENRY R. MINOR. 

